I don't like it.
Rawr.
I personally don't like any "Xion = Memories" theories at this point, but I like the idea of her being more connected to Naminé than to Kairi.
But some counterpoints:
-Nomura has stated very plainly that, while Xion is indeed a key character, the game is
not for her - it's for Roxas. So, wouldn't making the title of the game exclusively about her defeat the purpose of it not being a game for her?
-Some things point to Xion entering the Organization
before CoM. I'm talking about in the scene where Xemnas introduces Xion, he refers to the members of the Organization as "Ladies and Gentlemen". Larxene being the only female member at the time (before Xion was officially let in right there) would imply that the scene happened before her death in CoM, and possibly, even before CoM itself (depending on how long CoM really took place).
-Nami said that the memories that she would delink wouldn't leave his heart, but that they would just sink into the darkness of his heart.
I'll think of more, I'm sure, but other things need my attention